Restart on Track at Takahama 4 Nuclear Unit After Leak Fixed

A loose bolt caused a water leak at a nuclear power plant in Japan but will not lead to a delay in restarting the unit.

Kansai Electric Power Co. (KEPCO) said a loose bolt in piping at the 870-MW Takahama 4 nuclear unit caused about 34 litres of radioactive water to leak on the floor of the reactor auxiliary building.

Upon inspection, workers found water drops on two valves located above the puddle. The systems were isolated and pressurized to identify the leaking point in an inlet valve. KEPCO said water leaked from the valve as the system pressure temporarily increased during water feeding to the boron thermal regeneration system from the chemical volume and control system. Workers replaced the diaphragm sheet of the valve with a new sheet and verify if similar valves are appropriately fastened.

Takahama 3 and 4 were shut down in 2011 after the Fukushima Daiichi disaster. Takahama 3 restarted in January, and refueling of Unit 4 is underway.